AChiver Gchem

[silveryhair]

A What is the molality of 85% phosphoric acid, H3PO4, if the density of the solution is 1.70 g/ml?\

 

[Mamona]

Could you post the answer!!!

 

[Neil45]

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[Contach]

A What is the molality of 85% phosphoric acid, H3PO4, if the density of the solution is 1.70 g/ml?\

molality = mols of solvent/mass of solute = mols of H3PO4/mass of water (kg)

assume 1 L of solution = 1000mL
1000mL *1.70g/mL = 1700g of solution
if 85% is H3P04, you have 1700g*0.85 = 1445g H3PO4
1445g H3PO4 / 98g/mol = 14.7 mol of H3PO4

then, we had 15% water in 1L of solution, = 0.15L water = 0.15kg

molality = 14.74mols H3P04 / 0.15kg water = 98 molality

Hm... lol..

 

[doc3232]

molality = mols of solvent/mass of solute = mols of H3PO4/mass of water (kg)

assume 1 L of solution = 1000mL
1000mL *1.70g/mL = 1700g of solution
if 85% is H3P04, you have 1700g*0.85 = 1445g H3PO4
1445g H3PO4 / 98g/mol = 14.7 mol of H3PO4

then, we had 15% water in 1L of solution, = 0.15L water = 0.15kg

molality = 14.74mols H3P04 / 0.15kg water = 98 molality

Hm... lol..

That is a lot.